Warm Up (12-17-24)

What did the Bohr model assume about the motion of electrons?

• All electrons move in a circular orbit around the nucleus.

• Electrons do not have a specific path around the nucleus.

• • All electrons move in a single cloud layer around the nucleus.

• Electrons always remain in the same location around a nucleus.

Atoms have positively charged particles, negatively charged particles, and particles with no charge. Why is an atom electrically neutral?

• Atoms have the same number of electrons (negative charge) and protons (positive charge).

• An atom’s nucleus has only neutrons, which have no charge.

• Atoms contain subatomic particles and not electrically charged particles.

• Atoms have neutrons and protons in the nucleus, and they do not have a charge.

During a lab, a student stirs crushed ice into warm water. What assumption can the student make about the second law of thermodynamics?

• Both the ice cubes and the warm water gain heat, and thermal equilibrium is not reached.

• Both the ice cubes and the warm water lose heat, and thermal equilibrium is not reached.

• The ice cubes gain heat and the warm water loses heat until the temperature in the system is uniform throughout.

• The ice cubes lose heat and the warm water gains heat until the temperature in the system is uniform throughout.

Tags

NGSS.HS-PS3-4

1. What is always the direction of heat transfer?

• 1. From an object of greater mass to an object of less mass

• 1. From matter at higher temperature to matter at lower temperature

• From an object with greater thermal energy to an object with less thermal energy

• 1. From an object with less thermal energy to an object with greater thermal energy

Tags

NGSS.HS-PS3-4

1. The subatomic particle with a negative charge is the 

• proton

• neutron

• electron

• ion

1. How do endothermic reactions impact the overall kinetic energy of the molecules? Select all that apply.

• 1. Energy is absorbed during an endothermic reaction.

• 1. Energy is released during an endothermic reaction.

• 1. An endothermic reaction increases the average kinetic energy of the molecules ​​in the reaction mixture (the surroundings).

• An endothermic reaction reduces the average kinetic energy of the molecules in the reaction mixture (the surroundings).

Tags

NGSS.HS-PS1-4

1. Consider the scenario in which you are sitting by the campfire on a cold night. Which description best summarizes the heat transfer that occurs?

• 1. The burning of the wood absorbs energy from its surroundings. Heat is transferred from your body to the campfire. 

• 1. The burning of the wood releases energy to its surroundings. Heat is transferred from the campfire to your body.

• 1. The heat released by the campfire is balanced by the heat absorbed from its surroundings, so that the heat flow out of the system equals the heat flow into the system.

• 1. Heat does not flow between the campfire and your body, as thermal equilibrium already has been achieved.

Tags

NGSS.HS-PS3-4

1. How many electrons does one neutrally charged atom of argon have?

• 18

• 22

• 40

• 58

1. How many neutrons are there in Radium?

• 88

• 138

• 226

• 314

1. What is the lowest possible energy level that an electron can occupy?

• excited state

• fundamental state

• ground state

• outermost state